Earth picked up about 40,000 metric tons of interplanetary material, mostly dust, much of it from comets.

Earth lost around 96,250 metric tons of hydrogen and helium, the lightest elements, which escaped to outer space.

Roughly 505,000 cubic kilometers of water fell on Earth’s surface as rain, snow, or other types of precipitation.

Bristlecone pines, which can live for millennia, each gained perhaps a hundredth of an inch in diameter.

Countless mayflies came and went.

More than one hundred thirty-six million people were born in 2018, and more than fifty-seven million died.

Tidal interactions are very slowly increasing the distance between Earth and the moon, which ended 2018 about 3.8 centimeters further apart than they were at the beginning. As a consequence, Earth is now rotating slightly more slowly; the day is a tiny fraction of a second longer.